Industrial cleaning agents are used in industrial cleaning process to remove filth and reduce oil-water surface tension. Cleaning agents contain a large quantity of surfactant. In the agitation process, the surfactant will be absorbed around the bubbles to stabilize the bubbles, and thereby produce a large quantity of foams. Such a phenomenon is prominent in industrial processes such as cleaning of beer bottles, cleaning of heat-exchange equipment, boilers, and heat exchange pipelines, cleaning of steel sheets, cleaning of machines, and cement and starch pasting, etc. The existence of foams will cause degraded productivity, waste of raw materials and products, prolonged reaction period, degraded product quality, and environment pollution, etc. Therefore, foam elimination is of great importance. In industrial processes, defoamers are often added to eliminate foams.
Defoamers are mainly categorized into organic silicon defoamers and non-organic silicon defoamers by the active component. Most defoamers in heavy-duty powder detergent and heavy-duty liquid detergent products for drum-type washing machines are organic silicon defoamers, and siloxane defoamers are deemed as very effective in that application, because they can be used in low dosage and are not affected by water hardness; in contrast, conventional defoamer compositions, such as soaps, have certain requirements for water hardness. Most of best-selling organic silicon defoamers in the market are liquid products, and have drawbacks such as poor compatibility with the products to be defoamed and narrow applicability, etc., owing to the fact that they can not be added to solid products because they have high water content. In the cleaning industry, solid defoamers have their unique advantages.
Many research and development efforts have been made for solid defoamers: patent documents EP0496510A1 and EP1070526A2 introduce fatty acid, fatty alcohol, alkyl phosphoric acid, and nonpolar hydrocarbon additives with melting point 30˜100° C. as antifoaming ingredients; though these ingredients can form intermittent wax coating to encapsulate the active substances, they can not completely solve the problem of uneven distribution of the defoaming active substances; in EP1075863 and WO2005058454, the defoaming performance is enhanced by introducing a hydrophobic organic liquid; in WO2005058455, the foam elimination and suppression performance is enhanced by introducing a nonpolar additive with melting point 35˜100° C. and a non-silicon organic liquid; in EP1118655A1, the foam suppression performance of a silicone foam-controlling component is improved by adding oleyl alcohol; EP1075864A2 and WO2008043512 mainly introduce the organic silicon active substance, and do not put forth any restriction on the particle size of the carrier, such as sodium carbonate, sodium sulfate, sodium tripolyphosphate, and sodium borate. The particle can not absorb enough active substances and can not attain the expected defoaming effect if the particle size is too small; in addition, these patent documents do not describe how to make the active substances more easily to disperse and evenly agglomerate to the carrier; EP0636685A2, EP0718018A2, EP0995473A1, EP329842, U.S. Pat. No. 5,861,368, U.S. Pat. No. 6,165,968, WO 9716519A1, and U.S. Pat. No. 6,610,752 describe defoamers with zeolite as the carrier; viewed from the composition and structure, zeolite is in a porous “cage-type” structure, which can easily “trap” the defoaming active substances and will not give full play to the defoaming effect of the active substance. A large number of literatures have shown: the activity of defoamers with zeolite as the carrier will decay as the storage time increases. There are many counter measures against that problem: for example, encapsulate the active substances with protective film; introduce silicone polyether, so that the silicone polyether is absorbed to the carrier in advance to block up the porous structure of zeolite, or add wax substance that can form intermittent coating, etc.; however, all these measures can not completely solve the decay problem of the defoamers. CN1177630A describes a solid carrier based granular defoamer that can produce an alkaline pH when it is exposed to water, but the defoamer tends to absorb moisture when it is laid aside; EP142910 discloses the application of a water soluble or water dispersible organic carrier, which contains a first organic carrier component with melting point at 38˜90° C. and a second carrier component selected from oxyethylated non-ionic surfactant that achieves hydrophile-lipophile balance at 9.5˜13.5° C. and has melting point at 5˜36° C.; U.S. Pat. No. 4,894,177 describes a granular defoamer with modified cellulose as the carrier; US2003211961 describes a defoamer with the polymer, copolymer, or mixture of one or more acrylic resins as the carrier. In addition, the defoaming performance of all above defoamers has to be improved further.
Most of the solid defoamers described in above patent documents utilize carrier selection or utilize a combination of silicone grease and other auxiliary agents to attain the balance of foam elimination and suppression. However, these defoamers can not achieve ideal foam control effect in the early stage and late stage of washing, and can not ensure defoaming stability of the product, because it is difficult to achieve even distribution of the silicone grease in carrier if the silicone grease is not emulsified and dispersed in advance. It is a great concern of many specialists and scholars on how to achieve high foam control performance in the early stage and late stage of washing while maintaining defoaming stability of the product.
The inventor utilizes silicone emulsion to replace silicone grease and controls the silicone emulsion to agglomerate to the carrier in steps, forming two silicone grease adsorption “layers”; in that way, the problems of extremely high concentration gradient of silicone grease and uneven distribution of silicone grease resulted from agglomeration in one operation are alleviated, and enough defoaming component exists in the exterior part and interior part of the defoamer particles, achieving a slow release effect; hence, the foam elimination and suppression performance and stability of the product are improved. The prepared solid granular defoamer attains a preferable foam elimination and suppression effect in cleaning processes, such as cleaning of beer bottles, cleaning of heat-exchange equipment, boilers, and heat exchange pipelines, cleaning of steel sheets, cleaning of machines, cement and starch pasting, and powder detergent industry.